Expansion and tensioning device for aluminum alloy pistons



March 26, 1935. c. A. MARIEN ,7 EXPANSION AND TENSION ING DEVICE FOR ALUMINUM ALLOY PI STONS Filed March 19,. 1934 llwwurae: CH9? 55 H. MAE/EN.

and the cast iron cylinders.

Patented Mar. 26, 1935 UNITED STATES PATENT OFFICE Charles A. Marien, Stmlzluis,

ey Accessories tion, St. Louis, Mo.,

Mo., assignor to ufacturing Corporaa' corporation of Missouri Application March 19, 1934, Serial No. 718,229 3 Claims. (Cl. 309-12) My invention has relation to improvements in expansion and tensioning devices for aluminum alloy pistons and it consists in the novel features of construction more fully set forth in the specification and pointed out in the claims.

It is a matter of common knowledge in the automotive industry that alloy pistons must be longitudinally slotted in order to allow for the unequal degree of expansion between the pistons This slot introduces an element of weakness in the piston structure ultimately causing the piston to collapse in the lower part of the skirt and introducing a piston slap in operation. It has heretofore been proposed to correct this condition by placing steel expanding rings in the lower part of the skirt to restore the piston to its proper shape and reenforce the skirt so that it will again ride squarely on the cylinder wall and possess the proper degree of resiliency so that it will yield to excessive pressures placed upon it due to inequalities in the expansion of said cylinder wall. In the patent of Harold F. Phillips, Reissue No. 18,653, dated November 15, 1932, the principle of expanding a piston skirt in a direction at right angles to the pin bosses is disclosed, and in my Patent No. 1,887,769, dated November 15, 1932, a particular type of expanding ring is shown wherein the expanding ring is so shaped that pressure at right angles to the pin bosses is assured.

It is the object of the present invention to provide a simplified form of expander that merely requires the drilling of two oppositely disposed holes in the piston in order to securely mount the expander therein. As in the patents referred to, the disposition of the expander within the piston is such as to expand the piston skirt in a direction at right angles to the pin bosses and the expander is provided with suitable locking devices for permanently holding it in place. In one form of the invention the longitudinally disposed slot 'n the piston skirt is availed of to assist in holding the expander permanently in position.

The above advantages as well as others inherent in the invention will be better apparent from a detailed description thereof in connection with the accompanying drawing, in which:

Figure 1 is a side elevation of a longitudinally slotted piston with part of the wall broken away to show my improved skirt expander securely fixed within the skirt; Fig. 2 is'a vertical longitudinal section taken on the line 2-2 of Fig. 1; Fig. 3 is a perspective view of my improved skirt expander detached from the piston; Fig. 4 is a side elevation of a piston equipped with a modifled form of expander, a part of the piston skirt being broken away to expose a part of the expander Fig. 5 is a perspective view of a modified form of expander shown in Fig. 4; Fig. 6 is a still further modified form of expander; and Fig. 7 ,is a cross-sectional detail taken on the line 7-7 of Fig- 6.

Referring to the drawing, P represents a'piston provided with the usual pin bosses 1, 1 in which the piston pin 2 is lodged and having a' longitudinally disposed slot 3 in the piston skirt 4, according to the practice now common in the art.

E represents my improvedexpander formed of a sheet metal stamping and bent into the general shape of the letter U. The sides 5, 5 of the U- shaped expander are tapered inwardly slightly so that the terminal portions 6, 6 which ultimately engage the inner surface of the piston skirt are somewhat narrower than the arched portion 7 of the expander. The expander is, of course, made of spring steel and properly tempered so that when the terminal portions 6, 6 are forced together they will exert considerable outward pressure. Projecting outwardly from each terminal portion 6 of the expander is a locking pin 8 and the corners 9, 9 of each terminal portion 6 are bent outwardly to form prongs (as shown in Fig. 3). There is a second prong 10 bent outwardly from each edge e, e of the terminal portion 6 of the expander, the prongs 10 being spaced from the prongs 9 so that the four prongs on each terminal portion 6 will be rectangularly disposed and the pin 8 will project outwardly from within the rectangle of which the prongs 9 and 10 form the corners.

Before the expander E can be inserted into a piston P two holes 0 and o are drilled through diametrically opposite points on the piston skirt 4 approximately mid-way between the lower edge 11 of the skirt and the lower ring land 12, which holes are for the purpose of receiving the lock pins 8, 8. After having drilled the holes 0, o the operator merely forces the expander up into the piston, with the arched portion 7 adjacent to the head of the piston, until the pins 8, 8 snap into the holes 0, 0'. He .then presses the terminal portions 6, 6 firmly against the inner surface of the piston skirt until the prongs 9, 9 and l0, l0 bite into the soft alloy metal thereof and the expander E is firmly lodged. During the operation of the piston in the cylinder there will be a tendency for the prongs 9 and 10 to gradually imbed themselves into the piston skirt until the terminal portions 6, 6 lie flat against the inner surface thereof. It is apparent that the expander E cannot now become dislodged or even loosened as it is firmly anchored against movement in any direction.

In the modified form of expander E, shown in Figs. 4 and 5, instead of the prongs 9 and 10, I provide a pad 13 for one of the terminal portions 6, said pad being brazed onto the'expander or otherwise securely fixed thereto. The pad is provided with a centrally disposed tongue 14 inclined with respect to the pad to correspond with the inclination of the longitudinally disposed slot 3 in the piston skirt. A pin 15 projects outwardly from the pad slightly beyond the tongue 14 and a pin 16 also projects from the terminal portion 6 that is not equipped with a pad 13. The expander E is applied to the piston in a similar manner to the application of the expander E except that the expander is inserted into the piston so that the pad 13 will bear on the side provided with the slot 3, and when the pins 15 and 16 are lodged in the openings 0, o the tongue 14 of the pad will be lodged in the slot 3. Thus the pins 15 and 16 will prevent longitudinal movement of the expander within the piston skirt and the tongue 14 will prevent lateral shifting or tilting of the expander.

In the modified form of expander E shown in Figs. 6 and '7, there is involved the same principle of invention as shown in Figs. 4 and 5, except that in lieu of the pad 13 I form a tongue 1'7 in the metal of the expander itself. This simplifies the device somewhat as the tongue may be formed at the same time the expander blank is stamped out.

One of the advantages of the present expander is that it may be inserted into a piston without removing the piston from the cylinder and, of course, without disconnecting the connecting rod as it does not depend on any cooperation with the piston pin or piston pin bosses for holding it in place.

From the foregoing it is apparent that I have provided an extremely simple form of piston skirt expander capable of performing all the functions of a more complicated expander and embodying elements of construction that enable the expander to be lodged or firmly anchored within the piston skirt so that there will be no dislodgment of the same while the piston is in use.

Having described my invention, I claim:

1. A skirt expander for pistons comprising a U-shaped plate member of spring metal having skirt engaging portions at the ends of the U. a locking pin projecting outwardly from each skirt engaging portion, and a longitudinally disposed tongue on one of said skirt engaging portions.

2. A skirt expander for pistons comprising a U-shaped plate member of spring metal having skirt engaging portions at the ends of the U, a locking pin projecting outwardly from each skirt engaging portion, and a longitudinally disposed tongue on one of said skirt engaging portions intersecting with said locking pin.

3. A skirt expander for pistons comprising a U-shaped plate member of spring metal having skirt engaging portions at the ends of the U, a pad element securely fixed on one of said skirt engaging portions, a pin projecting outwardly from said pad and from the other skirt engaging portion, and means on said pad for preventing rotative displacement of the expander in the skirt.

CHARLES A. MARIEN. 

